Drive on I-94 just outside Chicago between Gary and Michigan City, Ind., and you catch a glimpse of the massive sand dunes that make up the Indiana Dunes National Lakeshore. Tucked between coal plants and steel mills, the dunes are as high as 200 feet, stretching along the southernmost tip of Lake Michigan.

These dunes were formed some 14,000 years ago, and most are now covered in forest, says park ranger Bruce Rowe, who has worked at the lake shore for 30 years.

“Most of the dunes at Indiana Dunes, people don’t recognize as dunes, because they’re hiding under an oak forest,” Rowe says.

But one dune, Mount Baldy, is different. It’s a big pile of sand with not a blade of beach grass to speak of, just a couple of scruffy trees struggling to survive.

Rowe says that’s partly because of the dune’s popularity. About 200,000 people visit the park each year, almost all to get their feet on Mount Baldy.

“For generations, people climbed up and down Mount Baldy, had a wonderful time,” Rowe says. “Along the way, [they] may have helped damage it in a small way as well.”

But the park didn’t take the damage seriously until last July, when 6-year-old Nathan Woessner of Sterling, Ill., was investigating a small depression in the sand in an area that was blocked off for restoration.

The depression suddenly gave way, swallowing him deep into the sand. Rescuers had to dig down 11 feet into the sand to get Woessner out after a three-hour burial. Rowe says Nathan was injured but has now fully recovered.

“We certainly don’t want to blame a 6-year-old for seeing a hole just outside the official area and wanting to investigate it,” he says. “That’s one of the reasons why the entire dune in the area is now closed, so that something like that doesn’t happen again.”